Guest Stars Keegan Allen as Toby Cavanaugh Janel Parrish as Mona Vanderwaal Tammin Sursok as Jenna Marshall Torrey DeVitto as Melissa Hastings Brendan Robinson as Lucas Gottesman Charles Hittinger as Sean Ackard Diego Boneta as Alex Santiago Carlson Young as Amber Co Starring Jill Holden as Mrs. Welch Robert Keith Wyatt as Chewy